Method for heating oil



March 14, 1933. A. E. HARNsBERGn-:R ET Al. 1,901,592

METHOD FOR HEATING OIL,

Filed Jan. 29, 1929 I do: wmf

Patented Mar. 14, 1933 UNITED. STATESV PATENT' oniricav A'UDLEY E.HABNSBERGER AND CLYDE L. SMITH, OF CHICAGO, ILLINOIS, ASSIGNORS T0 GYROPROCESS COMPANY, OF DETROIT, MICHIGAN, 'AYCORPORATION OF-MICT IGANMETHOD FOR HEATING o-IL Application led January 29, 1929. Serial No.335,834.

In the cracking of oil in the vapor phase it is customary to subject theoil first to temperatures sufficiently high to vaporize the oil butwithout substantially cracking the same.. The oil which remains inliquid form after being thus initially heated is removed from the systemwhile the vaporized frac-l tions thereof are separately passed into 'ahigh temperature or converting zone wherein said oil vapors are broughtto cracking temperatures and the conversion reactions are permitted tocontinue for a desired period of time. It has been found in theoperation of these systems that the vapors entering the cracking or hightemperature zone of the heating apparatus contain an appreciable amountof oil in liquid form, due, possibly, to entrainment. This liquid oil'inthe con; verting zone vris highly undesirable for the reason that itcollects on the highly heated walls of the tubes used in the crackingzone and produces a coke or carbon deposit which interferes seriouslywith heat transfer,-blocks the free passage of oil vapors through thetubes andl interferes inkmany other respects with the sustained orcontinuedoperation of commercial systems of thischaracter. p

It is therefore important to ldeprive oil vapors of all liquidentrainment before such vapors are admitted `into the high tempera?Vture cracking tubes, and it is to this end thatthe present inventionv isspecifically directed.

It is therefore an outstanding object of the invention to provide an oilheater for cracking o`il in the vapor phase wherein the heater is formedto include a setting divided by a transverse bridge wall into burner andtube compartments, the tube lcompartmentbeing provided with a seriesoftubes through which the oil vapors travel while being subjected to thedecomposition temperatures prevailing in the heater and wherein thefurnace gases after passing over said tubes, but

before leaving the settingand at relatively L low temperatures, arebrought into contact witha plurality of relatively enlarged tubesconstituting what is known as a preheating or drying'section, wherebythe waste heat of the furnace is utilized for heating the oil and oilvapor passing through said preheatingi bank to Vaporize the liquidcontent thereof before said vapors are admitted into the cracking tubesof the' appara-tus.

For a further understanding of the invention reference is to be had tothe followling description and to the accompanying drawing wherein:

Figure l is a diagrammatic View, partly in vertical section, of theapparatus employed in carrying out the present invention,

Figure 2 is a transverse sectional view on the line 2 2 of Figure l.

Figure 3 is a view showing a slightly modified form.

-Referring more particularly to the drawt 'l ing, the numeral ldesignates an oil furnace Y ror converter which is formed to comprise asetting 2 provided internally with vavertical transversely extendingbridge wall 3,- which divides the interior of the converter intoburnerand tube compartments 4 and 5 respectively. The burner compartment isprovided with oil burners or other combustion-devices 6 and thesefurnace gases'pass ,upwardly toward the roof 7 of the converter andvthen sweep downwardly through the tube-'compartment 5, finding exitfrein theV 1converter by way of the stack or`other outet.8; y

fArranged within the converter are longi tudinally extending rows orpasses of cracking tubes 9. k,The upper pass, indicated by l.thecharacters 9a, pass over the burner compartment 4, restsfon the top ofthe bridge wall 3 and also'yextends over the tubeco'mf partment 5. Thispassof tubes has its foirward' end connected with a header 10, while therear ends of the upper pass of tubes are connected by return bends, orother suitable means, with the lower passof tubes 9,- the convertedvapors leaving the outlet ends of the tubes 9 being passed linto-coolingand fractionating apparatus 11. v l' Arranged in the tube compartment 5below the tubes 9 is a bank of preheating or drying tubes 12. Thesetubes extend substantially at right angles to the tubes 9 and are l ofmaterially greater diameter. For example, the tubes lK9 may possess anoutside diameter of three inches, whereas the tubes 12 possess,

for example, an outside diameter of six inches or more. The tubes 12 arelocated in the relatively cooler portions of the converter. Thus thetemperature in the burner compartment may be as high as 2200 F., thetemperature in the upper portion of the tube compartment 1800 F., thetemperature around the preheating tubes 12 1300 F., and

the outlet temperature substantially 1200 F.

In carrying out the system oil is first passed through a tube still orvaporizer 13.where it is brought to a temperature of approximately 700F. This temperature is sufficiently high to vaporize the. desirablefractions of the oil but not to materially crack the same. The

oil leaves the vaporizer 13 and passes, into an evaporator 14, whichserves to separate the vaporized fractions of the oil from the liquidfractions, the latter being discharged from the bottom of the evaporatoras fuel oil. From the evaporator the vapors pass by way `of a pipe line15, in which is arranged a liquid trap' 16 to the inlet side of the,preheating tubes 12,-and enter said tubes at a temperature ofroughly,600 F. Thevapors are then passed through the tubes 12 and subjected tothe temperatures prevailing in the outlet side of the converter. Due tothe relatively large diameter of the tubes comprising the bank 12 andthe fact that these tubes are lo ated in the outlet portion of theconverter,

- the oil vapors passing through the tubes 12 are dried or preheated toremove therefrom all liquid lentrainment, with the result that when saidvapors are discharged from the tubes 12 and pass by way of a pipe line17 of thetubes 9. By reason of their relatively to the header 10 theyare in a substantially dry state whenl introduced into the inlet passlarge internal area the tubes 12 may be readily cleaned from time totime of such carbon from 80 to 100 degrees, and. this temperature orcoke deposit which may accumulate therein; The tubes `comprising thebank 12 are preferably connected so that the vapors pass' therethroughserially, since this tends to produce high velocity and good heattransfer.

Thel temperature rise in the vapors while passing lthrough the' dryingtubes varies is sufficient to thoroughly dry the vapors but notsuiiiciently high to overheat or appreciably crack the same. Forexample, the outlet vtemperature ofy the vapors when leaving the a.tubes 12 may be approximately 700 F.'

. In the present invention the coke which forms as a result of thedrying will not choke the tubes that are arranged in`parallel order,which is the arrangement in the bank 9. The

presence of coke, for example, in the entrance portion of the tubes 9ais extremely detrimental due tothe very high temperatures at the inletand which if present is apt to result in the burning out and mechanicalfailure of the tubes. Coke on the interior of the preheater-or drier 12,will not in any Vway be damaging since the furnace` temperature at thisypoint is in the neighborhood of 1200 T The tubes 12 can, therefore,

operate with small amounts of coke in them' for a period rof timewithout danger of burning out because of the low temperatures employed.One of the outstanding features of `this invention is that ofintroducing dry or slightly super-heated oil vapors into a crackingzoneror tube. t

7e prefer for reasons of economy to situate the preheating or dryingtubes in the converter setting. It is obviously within the scope of theinvention, however, to place these tubes ina separately heated element,as disclosed in Figure 3, the element being indicated by the numeral 18and is arranged as a part of the pipe line leading from the evaporator14 to the tubes`9.

What is claimed is.:

1. The method of cracking oil in the vapor phase, which consists inheating a continuously moving elongated stream of oil of re-.

stricted cross-sectional area tofa temperature y at which portionsthereof will vaporize without molecular decomposition, passing theheated oil to an enlarged zone and therein separating said vaporizedproduct from the portions which do not vaporize without moi leculardecomposition, then passing said vapors through an intermediateheatingZone in Yan elongated stream of restricted` cross-secpassing a movingstream of such oil-through a primary heating zone and therein heatingthe oil to a temperature at which portions thereof will vaporize withoutmolecular decomposition, substantially separating such vaporsin anexternally unheated zone from' the remaining portions of the oilwhich donot vaporize without molecular decomposition, passing said vapors in aconfined moving stream through an intermediate heating zone possessinga-higher temperature than said primary zone to effect vaporization ofthe entrainedunvaporlzed oil present 1n said vapors as a'mist orsuspensoid to reduce said vapors to a substantially dry moisture-freestate without permitting any appreciable cracking thereof to take place,then passing said dry vapors in a confined moving stream at a velocitymaterially greater than the velocity of the vapors in the intermediatezone through an elongated 'cracking zone of restricted cross-sectionalarea wherein said vapors attain a cracking temperature in excess of10000 F., and utilizing the same products of combustion which areemployed to heat the cracking zone to a high temperature for heating theintermediate drying zone to a lower temperature.

3. The method of cracking hydrocarbon oil in the vapor phase, whichconsists in passing a moving stream of such oil through a primaryheating zone and therein heating the oil to a temperature at whichportions thereof will vaporize without molecular decomposition,substantiallyV separating suchv vapors while removed from heatapplication from the remaining portions of the oil which do not vaporizewithout molecular decomposition, passing said vapors in a confinedmoving stream through an intermediate heating zone possessing a highertemperature than said primary zone to effect the vaporization of theentrained unvaporized oil present in said vapors as a mist or suspensoidwhereby said vapors are reduced to a substantially dry moisture freestate without appreciable cracking thereof taking place, and thenpassing said dry vapor in a confined moving stream at a velocitymaterially greater than the velocity of the vapors in the intermediatezone through an elongated cracking zoneof restricted cross-sectionalarea whereinv said vapors attain a cracking temperature in excess of1000 F.

4. The method of cracking hydrocarbon oil into vapor phase, whichconsists in passing a moving stream of such oil through a primaryheating zone and therein heating the oilto a temperature at whichportions thereof will vaporize without molecular decomposition,substantially separating such vapors in an externally unheatedseparating zone from the remaining portions of the oil which do notvaporize without molecular decomposition, passing said vapors in aconfined moving stream through an intermediate heating zone possessing ahigher temperature than said primary zone to effect the vaporization ofentrained unvaporized oil present in said vapors without any appreciablecracking of the vapors taking place, then directly passing said dryvapor from the intermediate heating zone and without reduction in itstotal weight through an elongated conversion zone "of restrictedcross-sectional area, wherein said vapors attain a conversiontemperature in eX- cess of T1000o F., and causing the vapors to travelat a materially greater vvelocity through said conversion zone than thevepossessing a higher temperature than saidl primary zone to effect thevaporization of entrained unvaporized oil 'present in said vaporswithout any appreciable cracking of the vapors taking place, thendirectly passing said dry vapor` from the intermediate heating zone andwithout reduction in its total weight through an elongated conversionzone of restricted cross-sectional" area, wherein said vaports attain aconversion temperature in eX- cess of l000 F., causing the vapors totravel at a materially greater velocity through said conversion zonethan the velocity of travel thereof through the intermediate dryingzona-and utilizing the same products of combustion which are employed toheat the con7'y version zone to a high temperature for heating theintermediate drying zone to a lower temperature.

In testimony whereof we affix our signatures.

AUDLEY E. HARNSBERGER. CLYDE L. SMITH;

